This invention relates generally to a magnetic tape cartridge, and more particularly to a tape guide employed particularly in a VTR magnetic type cartridge for guiding a magnetic tape. The invention also relates to a method of manufacturing a tape guide.
A conventional magnetic tape cartridge is formed by fitting together top and bottom cases each molded of a synthetic resin material, and fitting paired supply and take-up reels within the cavity formed by the top and bottom cases, with a magnetic tape wound on the supply reel and extending between the supply and take-up reels. The magnetic tape cartridge is provided with a plurality of tape guide members for guiding the magnetic tape through a predetermined passage and for attaining satisfactory recording and reproducing by stabilizing the running of the tape.
Conventionally, metallic guide members have been employed to reduce friction between the magnetic tape and tape guides and to prevent damage of the tape by the tape guides, thereby to attain smooth tape guiding as well as to mitigate or to completely eliminate problems liable to occur during the running of the tape. Furthermore, it is usual to form tape guides with a non-magnetic stainless steel material, to avoid magnetization of those guides. Accordingly, the smoothness of the surface of the tape guides is significant, as is the finishing of the tape contact surface of the guides.
A conventional tape guide formed with a nonmagnetic stainless steel material, however, has the disadvantages that the material is expensive and the production is high in cost and low in productivity, since the surface of the guide requires surface finishing, and stainless steel materials commonly have inferior machinability. Furthermore, the finished surface of the metallic tape guide is susceptible to being damaged after the surface finishing process but before the guide is incorporated into the cartridge; therefore, extremely careful handling is required of the metallic tape guide during this time. Such a requirement is one of the factors disadvantageously affecting the mass production of magnetic tape cartridges.
A tape guide made of a synthetic resin material has been proposed to eliminate the above-noted disadvantages of a metallic tape guide. However, such a guide has not been entirely satisfactory. Specifically, the proposed guide has the serious disadvantages that the friction between the guide and the tape is remarkably increased due to close adhesion of the tape to the smooth surface of the guide, and powder produced due to wear of the surface of the tape adheres to the tape surface, causing drop-out.
Accordingly, an object of the present invention is to provide a new tape guide which eliminates the disadvantages of conventional tape guides, and also a method of manufacturing the same.
The principal object of the present invention is to provide a tape guide of a synthetic resin and a method of manufacturing the same, wherein the tape guide is provided with many minute protrusions on the tape-guiding surface to greatly reduce the area of contact between the tape guide and the magnetic tape, thereby to decrease the friction between the tape guide and the magnetic tape and to attain stabilized running of the tape.
Another object of the present invention is to provide a method of manufacturing the tape guide requiring no machining process, especially the process for finishing the tape contact surface of the tape guide, and particularly suitable for mass-producing the tape guide. This object is achieved by utilizing a synthetic resin material of a molding contraction ratio of about 0.8% or greater.
A tape guide according to the present invention will be described in the following detailed description.